TY - JOUR

T1 - The 'Ice Hill'

T2 - An example of 'retarded deglaciation' in siberia

AU - Astakhov, Valery I.

AU - Isayeva, Lia L.

PY - 1988

Y1 - 1988

N2 - The geological structure of one of the southernmost sites of thick ice beds in the Yenisei valley near the Arctic Circle is discussed. The erosion contacts of the foliated and contorted ice, abundance of glacial debris and the position between the basal till and ablation cover indicate a glacial origin for the ice layer. The ice occurs in the cores of arcuate accretion ridges built of ablation materials. The overlying sequence consists of a series of diamicton flows alternating with lacustrine and outwash sediments. Laterally the ice-rock complex changes into thick lacustrine rhythmites underlain by basal tills. The ice-containing hummocky terrain is often lower than the adjacent lacustrine plain. Therefore inversion of ice-controlled topography is suggested. Several stages of glaciokarst development are supposed to have occurred after an eastward moving ice lobe stagnated more than 50 ka BP. The main depositional events are associated with the Middle Weichselian draining of ice-dammed Lake Igarka, and with Early Holocene topographic inversion. The Holocene warming apparently caused diapiric deformation of the buried ice probably because of the density and thickness differences between the ice and the overburden. The long history of burial and preservation of the remnants of basal glacier ice was controlled by Pleistocene permafrost. Landscape evolution in Northern Siberia is governed by such 'retarded deglaciation', in contrast with Atlantic environments. The thick ablation sequence may be described in terms of a Spitsbergen model, but the Siberian basal tills, because of their position within the permafrost, must be regarded as exfoliated layers of debris-rich ice according to Shantzer-Lavrushin's model. The occurrence of buried glacier ice and the mode of distribution of the permafrost shows the relict nature of the latter. In areas of modern and former retarded deglaciation intermittent diamicton flows are supposed to mark episodes of climatic amelioration like the Pleistocene and Holocene diamictons with driftwood at the 'Ice Hill'. Such 'warm' diamictons may account for some Early Holocene and similar puzzling interglacial 'ice advances'.

AB - The geological structure of one of the southernmost sites of thick ice beds in the Yenisei valley near the Arctic Circle is discussed. The erosion contacts of the foliated and contorted ice, abundance of glacial debris and the position between the basal till and ablation cover indicate a glacial origin for the ice layer. The ice occurs in the cores of arcuate accretion ridges built of ablation materials. The overlying sequence consists of a series of diamicton flows alternating with lacustrine and outwash sediments. Laterally the ice-rock complex changes into thick lacustrine rhythmites underlain by basal tills. The ice-containing hummocky terrain is often lower than the adjacent lacustrine plain. Therefore inversion of ice-controlled topography is suggested. Several stages of glaciokarst development are supposed to have occurred after an eastward moving ice lobe stagnated more than 50 ka BP. The main depositional events are associated with the Middle Weichselian draining of ice-dammed Lake Igarka, and with Early Holocene topographic inversion. The Holocene warming apparently caused diapiric deformation of the buried ice probably because of the density and thickness differences between the ice and the overburden. The long history of burial and preservation of the remnants of basal glacier ice was controlled by Pleistocene permafrost. Landscape evolution in Northern Siberia is governed by such 'retarded deglaciation', in contrast with Atlantic environments. The thick ablation sequence may be described in terms of a Spitsbergen model, but the Siberian basal tills, because of their position within the permafrost, must be regarded as exfoliated layers of debris-rich ice according to Shantzer-Lavrushin's model. The occurrence of buried glacier ice and the mode of distribution of the permafrost shows the relict nature of the latter. In areas of modern and former retarded deglaciation intermittent diamicton flows are supposed to mark episodes of climatic amelioration like the Pleistocene and Holocene diamictons with driftwood at the 'Ice Hill'. Such 'warm' diamictons may account for some Early Holocene and similar puzzling interglacial 'ice advances'.

UR - http://www.scopus.com/inward/record.url?scp=0024192913&partnerID=8YFLogxK

U2 - 10.1016/0277-3791(88)90091-1

DO - 10.1016/0277-3791(88)90091-1

M3 - Article

AN - SCOPUS:0024192913

VL - 7

SP - 29

EP - 40

JO - Quaternary Science Reviews

JF - Quaternary Science Reviews

SN - 0277-3791

IS - 1

ER -